A four-port transmission line device that processes two incoming RF signals of arbitrary phase and amplitude to output two corresponding RF signals of equal phase and amplitude. Two sets each of two quarter-wave transmission line segments are connected in series between corresponding input and ...http://www.google.com.tw/patents/US5717405?utm_source=gb-gplus-share專利 US5717405 - Four-port phase and amplitude equalizer for feed enhancement of wideband antenna arrays with low sum and difference sidelobes 
